The dynamic mediation model (Wilt, Noftle, Fleeson, & Spain, 2012) explains the associations between personality traits and happiness through links between personality states and daily well-being. To test this model, and the mediators of these relations, we examined if between- and within-person variation in personality was associated with daily well-being for undergraduates (N=133) and US adults (N=117). The model explained the trait neuroticism and daily well-being association. Also, after controlling for traits, people were happier on days in which they were extraverted, agreeable, conscientious, emotionally stable, and open to experience. Finally, these associations were partially mediated by the satisfaction of daily psychological needs. We discuss how the operationalization of state extraversion might impact its relation with daily well-being.